A method and a user device (1) for projecting a data file through a user device (1) are disclosed. The user device (1) has a reproducing device (1.7 ), means for identifying the user device (1) in a mobile radio network (5 ), and biometric recording means. The user is authenticated with the transmitted biometric data in a remote server (7 ) and downloads a data file to be projected or a key for decrypting a data file from the remote server (7 ) over the mobile radio network (5 ) in the user device (1). With the reproducing device (1.7 ) integrated in the user device (1), the data file or presentation is reproduced. The invention also concerns the disclosed user device (1).